SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55d992a162a24719dfe0d0019787afb786f1a51139280b97f297771b6d8ac944' 
  AND token = 'Kzm9s8GqVMQk7kUA7fi/jLCWdhoZWwZ72tAAc/kyB9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}