SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7357919485406af6f03cea2a94e13c523e21256f060dabe97d97f0869eb34bed' 
  AND token = 'WqAF+A1zmQ/2GrHvMh9kqBIKkl7bFzqNSzMQiW6pVg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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