SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37c53767d338c799539838a63ae28135f32ea166b7533e671eda0ebfc35c2742' 
  AND token = 'id9koy5zA0fvqzKpmO+Alw7j0lQXqUJOmBFCwZUQISA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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