SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd54a5168cc51cd55c54787b2c0011b1a68e1a5928a6a3bc4d214ee4a763a053' 
  AND token = '6iVQ1S+erESUIxMwM/nBJ9n3tY7ZlT1Yv3n8uA1VoIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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