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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '242ff7f16d92b014f78f1ab7300ab35588bd43fe28fa1b0219ebaa53ac7a19a1' 
  AND token = '6qGjzUt1BnCswTFMJ5TUCpyDe/mjI0dFN2XzXhHD4GU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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