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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6c5ceded33bbea8b4e0be5ca2e2e91550a052b49d78edc3083a1b4f7439dbde' 
  AND token = 'LvWgCtvd1ZZVWwVWRfHsWJSSzU3/jzUkm5MVPS1IHYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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