SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adbb7e5e557fc0f7fd94623f2a0a0628a79bf830982f5fe8245440602f662c12' 
  AND token = 'F//+JUhO+NjomyZ2ZuP+jD2edv1u4rpRtuVCVir4qL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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