SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f126ca829e2b58011707c15538458cab8083ceb58dc774700523a68b754bb74' 
  AND token = 'IWSeotkPGUEZUoQT3f2R3yGPwy+XgU9sY+yKCSH9SIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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