SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb47737147afe22b7defa80f88e01def98f11cc582b2faa028cce474de02d552' 
  AND token = 'H8wZDuviLrD07coew/VV8beLRRFuIixHTDIkErEiNgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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