SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2827854c8cb4ce312ff3912b19a0728160065e1204b27c4b1989c72a250917a' 
  AND token = 'oZK3L4ORqmyDhZjBSoj/Mo2/bwCdhYUl+Kg/Sd1vCr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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