SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c6d3fe85c76b643f237150d886283d0bd52cf11fc447c14a7a47cd43e377a54' 
  AND token = 'Ta8yiNVj+Scp2zm+sYNckEaToJQVECZaLskhc/qsXhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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