SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '394db1769aaab56b4d0faf46f320d2f23ab8de7642f51bb9b89fe549c5b5390e' 
  AND token = 'zKcvp7tq+BcXQ9SVwm355OPXxYm1rKgRuSUi5QKD5ks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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