SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cb96c227dedb058c956e84e5357de2bbbcb8b952758b5a817a04e0220318f02' 
  AND token = '6Jh+URUyF5uaFIL2Ukz/PN6Sg1maLp7uFLoMmOOqFDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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