SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcaaf8b97fda5576c19714354427095c0ad340145b535d6915eaf2f8dadc76df' 
  AND token = 'vr+Spc4KWQOkKBa/BOMxuBRwGxDRvpb/uRQOlLvui6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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