SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dff491d85e8102ae764dca1479d51bb97272ab037fb19ef728e8af67847adea8' 
  AND token = 'WuRsIy9kM6h/0R7+FYwIZwZxH126Iez3G522Vf6LT0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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