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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcd97febc48e430b9128b6628669bb3d4ed012b98273a30668df2206ae3e0a52' 
  AND token = 'eFQOe1LlxTL3KBHVBFgLfsXaUF99+weeXoS9SpV4aKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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