SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7493ce4df5fcee3739dfb17f5920ce1c517bfcfc1c50c7abe6a45574bb6ea236' 
  AND token = 'saEGAkWcwHf2Vv1pgEjYdDFsV5pjnfRi1SB4LBUGzNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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