SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c784cd9aa7bbea4ea4010915b55c81b31591877d7d406328c747a5d4fe02cc2' 
  AND token = 'HlhouGZsOQgkImAzEZdPn+3OAi/HfET+pUqQ/eCno/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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