SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35992c916a9452f394f78c70f1b0e6a0b8d3e228946766a29091736eb980395b' 
  AND token = 'BUGlGHXPO2gPeF2OkH2RQZqmBba9xUgv/GM8qChLKbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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