SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e2557c57d59d3609bffcab1a7958f477f337feda1a08adcc62d8ed0071d4aa' 
  AND token = '27gLzBcGDd/Q4hQxlHvIjfqqEV7LubQ69Nn++h4gcxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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