SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76aa5cbc490d6ba74311fb97666e52b8a9ea6033217d4954297a8134fc51a2a8' 
  AND token = 'KNV9YY7bJtpda6WtGZhnzOX+LlQwSiq9UD42jQ7oHPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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