SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9d66b9959fa2353141de533cb8a81fd5f2653604c7f084db0c4b332f6c8831' 
  AND token = 'EnEC598KANiGhfo0w9tRHLkwnYjtgWYkEeBR2EqD+LA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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