SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b56479c54d16d4e23ae23baf3e188566579263191199e1e3896d627f1892d8f4' 
  AND token = 'uZxLkFg0BYvd6xwP1GkqjgveIYgQarY4ivh2uq5NuSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}