SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '936be3aca5bbcaf0e32a89a6efc80ec036b9182712f525d3605c9a17b87745cf' 
  AND token = 'kVGB02wRsVxLpM1qJHQR94a4PBtRzcOkrmAcD4m+M68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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