SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2833a8b79c1004e621fb155001b74d721e5cca41dd39a1f896cf9a53c93b3dd' 
  AND token = '+3d1zKh+aI3/YY5p2n2DXrvCuaSIqj7+AHwMxth7LZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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