SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9dfcbb08fcee963ce34115a9c8b42f9242307f396408f91f65f3b8416871beb' 
  AND token = 'fb5FdZwYZq9m62KQ8HNAgKaFpBoL9v3KYKRGj/w/LGI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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