SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '762094c32ec8fe6c4c89846250c61a0c17915d3742875d1d3a6e153fcd256c89' 
  AND token = '8v9nAOqWiTEUXVZv4NUVaD5kcobUlgxRmQQ5Uv2Sf3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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