SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6802fca34ed25566a7f44c9fc4abc6635436cdbc41f56a9cf4e43eb53e5b2747' 
  AND token = 'AvHySRRuQGkKfioQC0ZAYq6WnYQw9PoXnx0E6IyyJWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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