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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '820979a2d2eb7aed186e9cafd5d68cd63e2e5688d84f5bb05d1a587e3ccbb706' 
  AND token = 'y6vWCdlw5cCSLWzYTpWtP0n4TW0sQpbJo/UatB3ziko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}