SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1e790bc153ff60d284e82829babb976df8c8a15a6c841709935ef1321d7d6e0' 
  AND token = 'kRor5sk99jQystM+gNsxzcvOrNQSWLd93kkNE16O9y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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