SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd542d16dc2f7d484de750368c1d91b3559b06c23010923905fc455057c5a4a2' 
  AND token = 'WJ4WA5DpG+WwZ4hzxueeynNBIgetU4VqHChbptlQWSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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