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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5a5dcc4815703da4eeeb5e7ba528c3c60a5e5e4d800b8b8afea2556e46f8db3' 
  AND token = 'rKt+wWmUesjJgOgZQbIEQzUMSi37/ERIxOHcFpJBKgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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