SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20c8e5263f9411758b559a24899b97fb3b68f21d637267a9fa69d67c4f6d8bc8' 
  AND token = 'Sm/ff//dgmiEw3eR8pejB8IKMvTTgIktmUX2DzPhu0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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