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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd9d7ef51d557ee51155f12a4731f20e7fdb0c7444f0ac74a2e7f4a180272bcf' 
  AND token = 'oxcVhRSfgZoq339Ud0CZzX7KhdPsDZvVlfTc3N/IFUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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