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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a9f827905fc644022ad50b0d9308c1951af72f301d7a5ae80b61a6e3aae48dc' 
  AND token = 'KInhlrc09Lki8T8Wq3USo8/F2LAT2sAlCkmxQ+63qUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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