SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0e8a13639175981bd33d8289f2e1571bbea82e40df9df3f46087450f76d5669' 
  AND token = 'MRF4qXgw2bLKEKu8ho/HGT7pPDvr+rdx3kSmPlZigSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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