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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d3fa320ab89a7a8d131ea73bd23b57b08f44609e24e19422a5cfe2dd50023ef' 
  AND token = 'AZkw/BOxoqLuzNEXAf9cY0Y+LQHw9A7ICIoBCdI28Qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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