SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'baa76e8757663a9a048f3140e14f81d05b5135adffe1ce7793386a0874867fa9' 
  AND token = 'm3QPmPoixhDdYuONF7TW9opPlSL+6Q4fCmUklz6p3Wk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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