SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f0ad3c8338cc7e183d39a7017c5e194ecaaf9b1e6f04ecd5bccd02366d0e11d' 
  AND token = 'HouEXIDzNd/BGlUT8CKfo5g0UcKRmvEz+BlbQdQVkaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00070

JSON explain

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