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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78d5d0e9ccf4855b373cc04ce6682866e39790d0b65aaa8f96f912f11c9cab96' 
  AND token = 'otyfgVXImorj93VRDoT+L956LtG+zZYjzFkE/EEWDjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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