SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe135deae935e3e29bfef1836c4b57876657f9c11b61f34dd75b802fcdb62472' 
  AND token = 'eOIBjrm+9UhjLB6u799qyWQyXVX+CXXgR9nyXZufgDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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