SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50bdf9c9ddec219800f98277c1badde8b6b70731e1a21552ceb85bef3698b527' 
  AND token = 'rEsBl8Fii7zBHQ8N/RjoKWhO0YRZp995MXFTWnPumSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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