SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3625fa79bf8bc5bae47bef6a0ad5c388bde08d209c232370cb65264e9110c40a' 
  AND token = 'cB5vps+pjf04qdXzQ7XCRE07L4dqwLcaC3wvgRTeNNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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