SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dae0be451e9397f8a5d340013be97b79857c67cfcc63dfaad2409145e55a86d6' 
  AND token = 'yEUPnWRQkHGg+QU28467h0LENHBLJWraHRhwgklZ4kI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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