SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfbb20114116dd52273118d0a4ab74af0d0b01b00a26fdeb6bfaa98161f02cfc' 
  AND token = 'BT5Tvitn+FmmN1NCzTrifgrT/Rwv8tnxabvRE/k3crM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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