SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '439ddb5d5242dac9ad2d73fb48389661e1961bb7ecf8d08a7bdcee7909daa491' 
  AND token = '2CnPzJaCoDmxMj6CwTmUQunCnWyMWp/xRZ/nLvZe0QY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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