SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51ec49667850400218be9e11226d388de2809bc3aecf6350dc131afc3438c608' 
  AND token = 'w/AhgwgXuI1BISE+ZP3wvJ95urZsveIlVrXzVUj3x1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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