SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc2717e0dbe7d4516d51487ae356127028b49fe8bb9d764178b103a5c22fc0f8' 
  AND token = 'uvh5v5ygpeTbF0SYVxQs16bufKiWCpOsBCRFPMzYsVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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