SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08b5c0b6920043d1588b554aab50f6541f8d0e2aa11c61ef266fc4602f2eaccf' 
  AND token = 'fDvJonkfjeowUGxqmO38h41SC4GGr7vNfeVMeOY9ESo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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