SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3248dcf5ebf234b77ed2b559abc77ec0177a8ff52ce350a74d3b1d05dfe29e31' 
  AND token = 'x18PB4sDq7po0VQI8YDyljt+OOiK3HDk2tWdHEWdIUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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