SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cddbc6afc3192b11ba0356d296249a0f1ded66f57b3c8dc45fda16daae589c51' 
  AND token = 'ta7WefSdmXARLwflKQZLdfVEyFPRv6WqzdGqnptiMi4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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