SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a74025bb000f168da51455216a52fb6d6b29161dec934fe990928ff4b440c2c' 
  AND token = 'YbYUqKrWCmtJxgmj0ao1EYMXb7EbAIy74IMQwD8zfzk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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