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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a308de7a3ce4c68fa95c85cb44d76acdd9024ba8be6e9919677b6fd9d4dfd1aa' 
  AND token = 'FiM6wVaHDC/g3UGE5fxApwqhfDnGnm1AAF3hlkyOLJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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