SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd20e594addb3e25f87feb905c7f64730c48d6b7036a02294e86440935f83f4dd' 
  AND token = 'MZspZg8AuG1UZS1Y0/BY5SPG8PVTpVfvDaXkwA32jCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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