SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398e7978a73a745def526187a4ad7daad1683b6d1be36df9227538b6c11ddc4c' 
  AND token = 'YyzYiF0t9ReLxlNFD2J164F7hTLO2EQhFZNzx4d1FXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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