SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b7fb57bf62f0976ddead41e8d9de5aab0cc249f5bb87252d5eb6aa029f31634' 
  AND token = 'TUUH/MACnp0SZ5wy3HTU5WOVRMzADnYWosCarpBVGhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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