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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a81d3563474f08b80ab5131820b0bbcd13ebb44a8fe111b4337033c6fa10f3ba' 
  AND token = 'k1lp5rBWpAQ9QTVDFw4x5WC72V9lBPe5/0lZpuZsKz0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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