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SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '55d7987adba1fb9458c36abc7ff80fadf0d8b18efccb5f3b3a7cfb3c64794b47' 
  AND token = 'TxHGuiwNQkKPpKDEknm8WNfaLkQxUeTjrwa3OxZ+f2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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