SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a842f0a88e5bf4f902d57cbb224b9b26be4d84a3fd69a7ddabbfb150ab8bfabe' 
  AND token = 'iV81FAYcH8/TE9HTwpQzbe6vRaAAivpZNz7SF+FJrTU=' 
  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"
    }
  }
}