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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40a6ffa03286c4cda6c76e2793b329c9b3b014286a8ba34d7bc94dfcb9d0a7d8' 
  AND token = 'jqb6nyBhCHf1e1+L2d1m/CRRi7P8fQF3JMB3awivJOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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