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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6ea0cd1d8045e10d71a90170495f2427362f0c6d2b617808ec00a979ca8be91' 
  AND token = 'XUZ6/UiwPxarSdGlidmbKy19x4+xJGnmAg1jMFiL1gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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