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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c9746bf3c5856c4eadf43735a959137a451617e9453259340b3c846336434ca' 
  AND token = '1ZB/fcJ8rGiuVga5TUenKu0foW4qZzySqxzJtvGQ68I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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