SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd35c4fe4988c0080b81329dfd327aff4be16468d5891819a3397317ff4cb93f9' 
  AND token = '8n4qxRN2zdRg2V/mkRktDVNVjN3GZ0ZYvGPKX1wQ3dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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