SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '183f103ea3ad5a41006b553f2138bc27e145126002246a320a025134174944a3' 
  AND token = '42/bfHWRtVLZujytt18OUBtyiIwNd8n3COaOR2KtmmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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