SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12c06ce02576998272adc788a785bf36d47c84ee0ae8ddc71f5dcb66e2245ac4' 
  AND token = '4ujMrrBjB6wkLpQN/yddWM2gA1UjhHQjCA1PWtGImFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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