SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '999e290d3b0bce6590ec256d5c26e7887d484c9b2df7652eeef21a5453381c0a' 
  AND token = 'eQ/6DOIGwb48iUgkptnfXD39zF8irn2JtdMPSdo5fko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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