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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ca74f03d66b68f9f9b14cf918cd1ed0bc33c0f69ee38eea4ee5180c4ca7936' 
  AND token = '4cgdwtQDYJ3bMofiraSUayBt4+o74UcIWPDRpdjwVxo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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