SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '588870302c4dcbf016a1cc6d1316dfe2db48e745645c6b3e635a61f654a0f5e8' 
  AND token = 'PReJMkDBQU1LzaM6RDjL7jo9BgNLoPXFnHT8qknjZJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}