SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2e7c03d52bf391206cbfb788b5c7fe84730c7595e022bc1e12a9b33f28f7ba6' 
  AND token = 'G/FXQ04eeBgJoMRy4c6cWdnVWvgfb+H/qkzvjB6JSTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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