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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00821ef4fe90ec425b93c604ba9a53e5a885a4b2ff0f04ec15ee2e6fde79afc6' 
  AND token = 'sehqF+0ybujgKFb5nTQ9rcoaI2MwqHK4SqUIDoA9kYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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