SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a13ee2d26d95924c7045d5bcc8c051b598c60329846c8c72369d51d2ba2b218' 
  AND token = 'YxlVFPl9mUzOcgDxkkuSHfQk1ceXlaCCs8w1aAu0xGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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