SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd1c57edfbd572f7592088a923a9f8eb74c257538653039239ce2e297e66f0c1' 
  AND token = 'dLftlR7JLle/iCVcvmwfhzOBw63p/vZlNloswiICjc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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