SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '336d8fef795e5bf0da3080c37933eb9986e914699cd249c0f6395e645c4af82b' 
  AND token = '3DeCIZJAIblPAJaX/X3/T7mcplcS+9F802+/uDKa77I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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