SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3f6df40daeb35856c1d186eea13f8d368100db28060d8ea9980171813fe8257' 
  AND token = 'qHp3lm5bNe0731kWlewrB3AT2aYbN9jvZUTs/ScUjiQ=' 
  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"
    }
  }
}