SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e874baf54fbb628e7a61793331bf6bc726f1abd1fbac530d4c50a3561d5d7926' 
  AND token = 'YqajLlYAKZG7HvCdLIf8+WDADMNmV9nO1626KbK2lh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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