SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7999960113539a109ef79596d2b5c273222d2fb9122050e3f2b58ce271dde8f' 
  AND token = 'vkdw7UUEchPzWpUVWYHxlVPE3Av2lLN2xhaB1Ne3EFs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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