SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '314432a8012708084c5bb2e7708215a17563aa6fc797af0aed2eccb115918254' 
  AND token = 'S6vsT36jaeXqn2thTqrbAgYidah65nLQlJ0PFSuHoek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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