SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6b1fb745690c9e781fbb187bdf8eb336a828859d17833f7a1719af97eb5616e' 
  AND token = 'RlHWCYtIjUsmvDpU4RtxlM02rRnVw9BeMTCij52PvhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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