SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5394570b2e01b296e86ca3fa42661b972f291ed8e6e3e276e9b76735c5675f0' 
  AND token = 'u5QiFib15ejdSCjbUXtGst9p6Q4m/cf/oo54JveVygQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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