SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbf0a3a8cf8bb72a6d2d1d75e350ff1d7cf42ef892c0a439733aaee43dc3067d' 
  AND token = 'fYxHVmiFmriIHEjXUvoJCLgY8NGCX+r/jB8SNxbiTFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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