SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a517bb4c039b808a392ed60738b3766b891684ef79fb9868ee3f24faeaf6c4' 
  AND token = 'N0TRb+1I2AnwlvVgf2sMgGxC/lTheleuffo4AebK0lU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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