SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42cd30398408b26d3a8fb7b350206e0f3ec13c6d0914c1c2ae4dc011b3d76305' 
  AND token = 'dDOO/a4paZQggVMqWdnaxTqqxNix0VoQM8usCtssVYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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