SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835b1ba2d56241679e9e8edb5f0159627605841b343380030201e244559692d4' 
  AND token = 'WtaMqsHP5DjvRaBbJKAAyzPxcyHdB0OBlxtSmpuWkvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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