SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b83d4761a54056c70b1a8be5b1e2a6cd438fcd1ce5e8177e7241b3c5f2355842' 
  AND token = '2mYL4O389rFqTvgb1/7VhISe7Q5/tXxa7Frkto9Ns3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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