SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f76b70c91714815d8fbf0505101a9253ea5952db46b695cbfd592eae349a5c6a' 
  AND token = 'PRN2hLYjxwD/VSU4i/UUVsFS8QYbUFZkRR+QUuuYmQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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