SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcc77b61e3a9bb467ce6468dd907c1d493ee72edf9e293f8720196e0abe2a0f0' 
  AND token = 'z5nCb6JjUBdxNuuIOVJITz6zi4sgWPOr9JfUKcZX8y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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