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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df6da74e08e4dffaf801c28d80e9ca21bc58def59c8eb5c2a2dbfea3fa28ef08' 
  AND token = 'PpFs5N+XjLi980jQYhfz0hmqhkC2LvjItR/FaBtc0qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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