SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2bcd1aad31a7e233bce766fe4fca322fe68178b55360a844cce68aa088493166' 
  AND token = 'JQSUkYxfcnefP4VezzTEYoqrbh93F1Dc2CmohvDkNjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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