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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5dcd2ad3fde9bf6b8f204f2d55e64cfc91e694ab8604ab25be1e4b6663f8388' 
  AND token = 'iTSy/xDQqb6khbvW2cYlLYvIKZK1a23RIB/hvzALHL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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