SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de98c17b39ef4b89786cb71aa8d2d2e5ea6bdf35acc49b3e56ddcba50954035b' 
  AND token = 'eh6iZGBrjQwCcV8wSSj8ZNL9i50q2SNbvTNYMt+qrwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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