SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71a497483ba8c874049db1694c05f163f94ad0905c0de37b08ea0bffdc6d26da' 
  AND token = '1GcuV4sZY89DrrRLeOcqRSiKgvo44ZLCmhdQ8t2uDJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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