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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f76bc36214519d9ac9eebfad87bb3f11382c3aa1ff0a015d7ac7ac98b691978' 
  AND token = 'nEzjCOHKmpUU1WqbNNCPW0eEWuTCGlMd9Y5dUTwgNpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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