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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37a5e8af2a9f26b5ba44e3c2c3968c367e4cea6dd4dedf1c2c38f5c7142af98e' 
  AND token = 'RQ9IkpIy3ZI/RqRZ8dk99PnUdAYhku+eGSVbrLIfOXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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