SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ec83d04aad9834be7256456b501df36f4dff37fc3b4d3df07d4c67205cff73e' 
  AND token = '9295m/gFL7xYgSSLeISTkinWSMLGx4ZlnpTpT+CJlsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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