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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a753c24f67a52ab7df76715454a6fc3b86f44545c9eef1aa6fa41049ed0d4f52' 
  AND token = 'NdsEpubgYxiFSHZDC04bXJ3XzMNajMWxdNA2UC5v8ao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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