SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d61c26cb6ce95b35575647eb092fdad9aba1b9ae58c52f206b5e2a03b278317' 
  AND token = 'T5nGac+IRkN+yCd6AdkVBXNNtpUMPoy+veiOPGizWjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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